Instead of earning himself a simple trip to the principal’s office, a terrified 7-year-old boy was hauled out of class, handcuffed like a hardened criminal and “interrogated” by police for a grueling 10 hours — all over a playground dispute involving $5, his family is charging.

“My son was crying, ‘Mommy, it wasn’t me! Mommy, it wasn’t me!’ I never imagined the cops could do that to a child. We’re traumatized,” Wilson Reyes’ distraught mom, Frances Mendez told The Post last night.